Centrifugal clutch

Abstract

A vehicular centrifugally operated master friction clutch ( 20 ) for coupling an engine ( 18 ) to a transmission input shaft ( 28 ). The clutch includes flyweights ( 110 ) pivoted to a drving member ( 60 ) rotatable with the engine. Rollers ( 120 ) fixed to the flyweights act on ramp surfaces ( 148 ) to apply an axial clamping force (CF) to friction members of the clutch driving and driven member. The clamping force is applied through a spring compression ( 132 ) to limit the magnitude of clamping force.

I claim:  
     
         1 . A vehicular centrifugally operated master friction clutch ( 20 ) for coupling an output member ( 136 ) of an engine ( 18 ) to a transmission input shaft ( 28 ), said clutch including a driving member assembly ( 60 ) rotatable with said engine output member and a driven member assembly ( 62 ) rotatable with said transmission input shaft, said clutch comprising: 
 a plurality of flyweights ( 110 ) carried by said driving member assembly for rotation therewith and radial movement relative thereto;    return members ( 114 ) urging said flyweights radially inwardly;    wedging members ( 120 ) fixed to said flyweights for radial movement therewith, said wedging members received between opposed surfaces ( 124  and  126 ) of a relatively axially fixed reaction plate ( 125 ) and an axially movable plate ( 128 ), one of said surfaces ( 126 ) defining a ramped portion ( 148 ) extending radially outwardly and axially toward the other of said surfaces whereby as said wedging member moves radially outwardly along said ramped portion said axially movable plate will be urged in an axial direction away from said reaction plate;    an axially movable pressure plate ( 130 ) rotatable with said driving member assembly for applying a clamping force (CF) to frictionally engage a friction member ( 140 / 142 ) rotatable with said input shaft with a friction member ( 136 A/ 104 / 130 A) rotatable with said driving member, and    a resilient member ( 132 ) axially interposed between said axially movable plate and said pressure plate for limiting the magnitude of said clamping force.    
     
     
         2 . The centrifugally operated master friction clutch of  claim 1  wherein said engine has a known idle speed and said flyweight and return members are configured such that said wedging members will be positioned radially inwardly of said ramped portion of said surface when said driving member is rotating at a speed no greater than said idle speed.  
     
     
         3 . The centrifugally operated master friction clutch of  claim 1  wherein said output member is an engine flywheel ( 136 ).  
     
     
         4 . The centrifugally operated master friction clutch of  claim 1  wherein said flyweights are pivotably ( 112 ) mounted on said driving member assembly.  
     
     
         5 . The centrifugally operated master friction clutch of  claim 1  wherein said return members are compression springs.  
     
     
         6 . The centrifugally operated master friction clutch of  claim 1  wherein said wedge members are rollers rotatably carried by said flyweights.  
     
     
         7 . The centrifugally operated master friction clutch of  claim 1  wherein said relatively axially fixed plate ( 125 ) is associated with a wear adjustment mechanism ( 125 A).  
     
     
         8 . The centrifugally operated master friction clutch of  claim 1  wherein said resilient member is a compression spring.  
     
     
         9 . The centrifugally operated master friction clutch of  claim 1  wherein said resilient member is a belleville washer.  
     
     
         10 . The centrifugally operated master friction clutch of  claim 1  wherein said clutch has a degree of engagement dependent upon the rotational speed of said driving member, said clutch being disengaged when said driving member is rotating at said engine idle speed, said clutch becoming incipiently engaged when said driving member is rotating at an incipient engagement engine speed (ES IE ) greater than said engine idle speed (ES IE >ES IDLE ), said clutch achieving a maximum engagement ( 74 / 76 ) when said driving member is rotating at at least a lockup engine speed (ES LOCKUP ), said lockup engine speed greater than said incipient engagement engine speed (ES LOCKUP >ES I E), said clutch remaining at maximum engagement when said driving member is rotating at a disengagement engine speed (ES DISENGAGE ) less than said lockup engine speed (ES LOCKUP >ES DISENGAGE ).  
     
     
         11 . The centrifugally operated master friction clutch of  claim 1  wherein said surface ( 126 ) defining said ramped portion ( 148 ) defines a further portion ( 150 ) located radially outwardly of said ramped portion and not extending axially towards said other surface ( 124 ) whereby movement of said wedging member radially outwardly along said other portion will not further urge said movable plate axially away from said reaction plate.  
     
     
         12 . A vehicular drivetrain ( 10 ) comprising an engine ( 18 ), a change gear transmission ( 12 ) and a centrifugally operated master friction clutch ( 20 ) for coupling an output member ( 136 ) of said engine to a transmission input shaft ( 28 ), said centrifugally operated master friction clutch including a driving member assembly ( 60 ) rotatable with said engine output member and a driven member assembly ( 62 ) rotatable with said transmission input shaft, said drivetrain characterized by: 
 said clutch comprising: 
 a plurality of flyweights ( 110 ) carried by said driving member assembly for rotation therewith and radial movement relative thereto;  
 return members ( 114 ) urging said flyweights radially inwardly;  
 wedging members ( 120 ) fixed to said flyweights for radial movement therewith, said wedging members received between opposed surfaces ( 124  and  126 ) of a relatively axially fixed reaction plate ( 125 ) and an axially movable plate ( 128 ), one of said surfaces ( 126 ) defining a ramped portion ( 148 ) extending radially outwardly and axially toward the other of said surfaces whereby as said wedging member moves radially outwardly along said ramped portion said axially movable plate will be urged in an axial direction away from said reaction plate;  
 an axially movable pressure plate ( 130 ) rotatable with said driving member assembly for applying a clamping force (CF) to frictionally engage a friction member ( 140 / 142 ) rotatable with said input shaft with a friction member ( 136 A/ 104 / 130 A) rotatable with said driving member, and  
 a resilient member ( 132 ) axially interposed between said axially movable plate and said pressure plate for limiting the magnitude of said clamping force;  
   said engine having a known idle speed; and    said flyweight and return members configured such that said wedging members will be positioned radially inwardly of said ramped portion of said surface when said driving member is rotating at a speed no greater than said idle speed.    
     
     
         13 . The drivetrain of  claim 12  wherein said centrifugally operated master friction clutch has a degree of engagement dependent upon the rotational speed of said driving member, said clutch being disengaged when said driving member is rotating at said engine idle speed, said clutch becoming incipiently engaged when said driving member is rotating at an incipient engagement engine speed (ES IE ) greater than said engine idle speed (ES IE >ES IDLE ), said clutch achieving a maximum engagement ( 74 / 76 ) when said driving member is rotating at at least a lockup engine speed (ES LOCKUP ), said lockup engine speed greater than said incipient engagement engine speed (ES LOCKUP >ES IE ), said clutch remaining at maximum engagement when said driving member is rotating at a disengagement engine speed (ES DISENGAGE ) less than said lockup engine speed (ES LOCKUP >ES DISENGAGE ).  
     
     
         14 . The drivetrain of  claim 12  wherein said surface ( 126 ) defining said ramped portion ( 148 ) defines a further portion ( 150 ) located radially outwardly of said ramped portion and not extending axially towards said other surface ( 124 ) whereby movement of said wedging member outwardly along said other portion will not further urge said movable plate axially away from said reaction plate.  
     
     
         15 . A vehicular centrifugally operated master friction clutch ( 20 ) for coupling an output member ( 136 ) of an engine ( 18 ) to a transmission input shaft ( 28 ), said clutch including a driving member assembly ( 60 ) rotatable with said engine output member and a driven member assembly ( 62 ) rotatable with said transmission input shaft, said clutch comprising: 
 a plurality of flyweights ( 110 ) carried by said driving member assembly for rotation therewith and radial movement relative thereto;    return members ( 114 ) urging said flyweights radially inwardly;    actuation members carried by said flyweights for movement therewith, said actuation members acting on an axially movable plate ( 128 ) whereby as said flyweights move radially outwardly said axially movable plate will be urged in an axial direction away from an axially fixed reaction plate;    an axially movable pressure plate ( 130 ) rotatable with said driving member assembly for applying a clamping force (CF) to frictionally engage a friction member ( 140 / 142 ) rotatable with said input shaft with a friction member ( 136 A/ 104 / 130 A) rotatable with said driving member, and    a resilient member ( 132 ) axially interposed between said axially movable plate and said pressure plate for limiting the magnitude of said clamping force.    
     
     
         16 . The centrifugally operated master friction clutch of  claim 15  wherein said engine has a known idle speed and said flyweight and return members are configured such that said actuation members will be positioned not to urge said axially movable plate when said driving member is rotating at a speed no greater than idle speed.  
     
     
         17 . The centrifugally operated master friction clutch of  claim 15  wherein said flyweights are pivotably ( 112 ) mounted on said driving member assembly.  
     
     
         18 . The centrifugally operated master friction clutch of  claim 15  wherein said return members are compression springs.  
     
     
         19 . The centrifugally operated master friction clutch of  claim 15  wherein said actuation members are rollers rotatably carried by said flyweights.  
     
     
         20 . The centrifugally operated master friction clutch of  claim 15  wherein said relatively axially fixed reaction plate ( 125 ) is associated with a wear adjustment mechanism ( 125 A).  
     
     
         21 . The centrifugally operated master friction clutch of  claim 1  wherein said resilient member is a Belleville washer.